title: Regulation of poly(ADP-ribose) polymerase-1 functions by leukocyte elastase inhibitor/LEI-derived DNase II during caspase-independent apoptosis.
abstract: Poly(ADP-ribose) polymerase-1 (PARP-1) is an important regulator of apoptosis. Its over-activation at the onset of apoptosis can inhibit the action of apoptotic endonucleases like caspase-activated DNase and DNAS1L3. Therefore, controlled PARP-1 proteolysis during caspase-dependent apoptosis is considered essential to promote DNA degradation. Yet, little is known about the interplay of PARP-1 and endonucleases that operate during caspase-independent cell death. Here we show that in the long-term cultured HeLa cells which undergo caspase-independent death, PARP-1 co-immunoprecipitates with leukocyte elastase inhibitor-derived DNase II (L-DNase II), an acid DNase implicated in this death pathway and activated by serine proteases. Our results indicate that, despite having putative poly(ADP-ribose)-acceptor sites, LEI/L-DNase II is neither significantly poly(ADP-ribosyl)ated nor inhibited by PARP-1 during caspase-independent apoptosis. Unexpectedly, caspase-independent apoptosis induced by hexa-methylene amiloride, LEI/L-DNase II can activate PARP-1 and promote its auto-poly(ADP-ribosyl)ation, thus inhibiting PARP-1 activity. Moreover, overexpression of LEI blocks the pro-survival effect of PARP-1 in this model of cell death. Our results provide the original evidence for a new mechanism of PARP-1 activity regulation in the caspase-independent death pathway involving LEI/L-DNase II.
authors.affiliation: Université Pierre et Marie Curie-Paris 6, France; Université Paris Descartes-Paris 5, France. chloe.daniel@inserm.fr
authors.forename: C
authors.initials: C
authors.lastname: Leprêtre
authors.forename: A I
authors.initials: AI
authors.lastname: Scovassi
authors.forename: G M
authors.initials: GM
authors.lastname: Shah
authors.forename: A
authors.initials: A
authors.lastname: Torriglia
mesh_terms: D017209:Apoptosis / Q000502:physiology; D016923:Cell Death / Q000502:physiology; D002460:Cell Line; D002470:Cell Survival / Q000502:physiology; D003851:Deoxyribonucleases / Q000378:metabolism; D004706:Endodeoxyribonucleases / Q000378:metabolism*; D006367:HeLa Cells; D006801:Humans; D000071137:Poly (ADP-Ribose) Polymerase-1; D011065:Poly(ADP-ribose) Polymerases / Q000378:metabolism*; D015843:Serpins / Q000378:metabolism*
chemical_list: D015843:Serpins; C075177:SERPINB1 protein, human; C499320:PARP1 protein, human; D000071137:Poly (ADP-Ribose) Polymerase-1; D011065:Poly(ADP-ribose) Polymerases; D003851:Deoxyribonucleases; D004706:Endodeoxyribonucleases; C109663:caspase-activated deoxyribonuclease; C019329:deoxyribonuclease II